低磁场冷冻对鲢鱼肌原纤维蛋白的作用

Effect of Low Magnetic Field Freezing on Structural and Functional Properties of Myofibrillar Proteins in Silver Carp Muscle

采用2 mT低磁场(low magnetic field,LMF)冷冻、0 mT磁场(no magnetic field,NMF)冷冻和常规冷冻(conventional freezing,CF)技术对3组鲢鱼肌原纤维蛋白进行为期28 d的冷冻实验。通过表面疏水性、巯基含量、溶解度、浊度、热稳定性、傅里叶变换红外光谱、内源性荧光光谱和紫外吸收光谱各项指标考察蛋白的结构和功能性质变化。结果表明:施加低磁场冷冻可以抑制蛋白聚集和内部疏水基团的暴露,且能抑制α-螺旋的展开,减弱α-螺旋向β-折叠转变的能力,并维持良好的二、三级结构稳定性;CF组的蛋白总巯基含量、溶解度和浊度与NMF组相比无显著差异,由于冷冻温度较低,对蛋白聚集和内部疏水基团的暴露有一定的抑制作用,同时也使得蛋白结构变得松散不稳定;与CF组相比,LMF组同样显示出对蛋白的结构和功能有较好的保护和改善作用。总体来说,低磁场冷冻可以抑制肌原纤维蛋白变性并维持良好的结构和功能,且与常规冷冻(-30℃)相比,低磁场冷冻(-20℃、2 mT)可以节约10℃的冷冻温差,预测其具有一定的节能潜力。

In this study,2 mT low magnetic field(LMF),0 mT magnetic field(NMF),and conventional freezing(CF)were used to conduct a 28-day freezing experiment on myofibrillar proteins of silver carp muscle.Changes in the structure and functional properties of the proteins were investigated by measuring surface hydrophobicity,sulfhydryl content,solubility,turbidity,thermal stability,Fourier transform infrared(FTIR)spectra,endogenous fluorescence spectra,and ultraviolet(UV)absorption spectra.The results showed that the application of LMF freezing could inhibit protein aggregation,exposure of interior hydrophobic groups,andα-helix unfolding,weakenα-helix toβ-sheet transition and maintain good secondary and tertiary structure stability.There was no significant difference in total sulfhydryl content,solubility,or turbidity between the CF and NMF groups.As it provided lower freezing temperatures,CF inhibited the aggregation of proteins and the exposure of interior hydrophobic groups,but simultaneously made the protein structure sparse and unstable.Compared with CF,LMF freezing could better protect and improve protein structure and function.Overall,LMF freezing can inhibit protein denaturation and maintain good protein structure and function.Compared with CF(−30℃),LMF freezing(−20℃,2 mT)has the potential for energy saving.